Nelson's sharp-tailed sparrows have sunny, golden-orange feathers from their eyebrows down to their breast, where they also have darker stripes. The tops of their heads have gray stripes and dark brown borders. The feathers covering the ears are gray. Their necks and upper bodies are olive-brown and streaked with white or gray. White extends down the belly to a brown tail that ends in a point. They are small birds that weigh about 19 to 21 g. They measure 11 to 13 cm long and their wingspan is about 20 cm long. Both males and females look similar, but males are slightly larger than females. Juveniles have brown ear feathers and the markings on their face are less noticeable. (Cooper and Beauchesne, 2004; "Ammodramus nelsoni", 2011)
There are three main groups of Nelson's sharp-tailed sparrows in North America. One group lives around Hudson Bay in Canada. The other two live in both Canada and the United States. One lives along the north coast of the Atlantic Ocean from Quebec down to Maine. The other lives in the center of North America, from Minnesota and northwest North Dakota to Alberta and northwestern Canada. All groups travel to spend the winter along the coast of the southern Atlantic Ocean and the Gulf of Mexico. A small number spend the winter on California’s coast. (Cooper and Beauchesne, 2004; "Ammodramus nelsoni", 2011)
Nelson's sharp-tailed sparrows live in grassy wet habitats like marshes and wetlands. They are often found in freshwater marshes, grassy acidic bogs, and wet meadows. They prefer to nest in willow trees, so they are often found where there are a lot of willow trees. They prefer areas where where the water is 1 to 10 inches deep. This is most important during the breeding season, and they won't live somewhere that's too wet or too dry. Nelson's sharp-tailed sparrows spend the winter in saltwater marshes on the coast. (Cooper and Beauchesne, 2004; "Ammodramus nelsoni", 2011)
Each male mates with more than one female in the same breeding season. In courtship, females crouch with their tail and bill raised, wings folded and a little bit raised. They don't make any sound. Males search for female mates. (Greenlaw and Rising, 1994)
Nelson's sharp-tailed sparrows breed once a year during the spring and summer. Females make a nest near the ground shaped like a cup. The nest is attached to reeds or willow branches, and must be high enough off the ground so that it doesn't get flooded. Females lay 3 to 7 eggs, and keep them warm for about 11 days until they hatch. After 10 more days, young are able to fly and leave the nest. Mothers care for the chicks for 20 more days, and then they are able to be independent. (Cooper and Beauchesne, 2004)
Females build nests and keep the eggs warm. After the eggs hatch, females cover them to keep them warm for 2 to 6 minutes at a time. Young chicks really only eat invertebrate prey that mothers find in nearby plants, mud, and water. Males sometimes bring food to the nest as well. After the young have left the nest and begin to fly, they stick together in a group with their mother and siblings for 20 days. However, mothers do not defend the nest if there is a predator nearby. They will fly away and stay quiet and hidden nearby. After the chicks have left the nest, females make alarm calls to warn the young about predators. (Shriver, et al., 2011)
The longest recorded lifespan in the wild of a Nelson's sharp-tailed sparrow is 10 years for a male and 6 years for a female. These records come from catching birds, tying bands around their ankles, and catching them again. This means that some birds may live longer, but those are the oldest that were caught twice. (Shriver, et al., 2011)
Nelson's sharp-tailed sparrows spend most of their time searching for food, except that males in the breeding season spend a lot of time singing and looking for females. When searching for food, they run in short spurts, walk, or hop if looking for insects. If they are not looking for food, they often climb up to the top of plants to look around the area. If they are startled, they run crouched down close to the ground with their heads lowered. (Greenlaw and Rising, 1994)
Males usually only meet if one male forces another off a perch, or if one retreats when another comes close. Many songbirds sing competing songs, but Nelson's sharp tailed sparrows don't do this. Males may stop singing if another male approaches or sings nearby. Females sometimes fight with males or chase them away from the nesting area with threatening calls or body language. (Greenlaw and Rising, 1994)
Nelson's sharp-tailed sparrows migrate, traveling between a summer and winter location. When migrating, they are often spotted feeding in groups of 10 to 40. If there is a lot of food available, there can be up to 100 of them in the same group. (Greenlaw and Rising, 1994)
Males don't have territories, and will even share perches they sit on with other males. Their home range, or general area where they live, is about 1.2 to 1.6 hectares in New Jersey and 3.0 to 5.7 hectares in New York. Scientists think their home range in Canada in much bigger, but they haven't measured it yet. (Greenlaw and Rising, 1994)
Males attract females with their songs, but don't use songs to mark territories like many songbirds do. They often sing while flying. Most often, their song sounds like "k-chinnnng doot," like two short chips with dry hiss in between. Females don't sing, but they make short warning calls to alert young about danger. They also make threatening calls to ward off other males from their nests. During courtship, they communicate using body language. Their most important senses are sight, sound, taste, smell, and touch. (Greenlaw and Rising, 1994)
Nelson's sharp-tailed sparrows are omnivores, so they eat both plant and animal foods. Most of the foods they eat are found on grass stems or on the ground. In warmer months, they eat insects, spiders, and other small invertebrates. In the winter, they eat mostly seeds and grains. (Shriver, et al., 2011)
If a predator comes near, females silently move away from their nests and hide. Mothers will give warning calls to young chicks and fly within 10 to 15 m of the nest. Females return after the possible predator leaves. They may make alarm calls if there is a flying predator, but usually just hide quietly. Their brown, gray, and black feathers blend in well with their grassy environments, giving them camouflage. Predators of Nelson's sharp-tailed sparrows and their nests include northern harriers, short-eared owls, fish crows, Norway rats, and garter snakes. Other suspected predators include herons, egrets, glossy ibises, American crows, and black snakes. (Greenlaw and Rising, 1994)
Nelson's sharp-tailed sparrows probably distribute seeds and impact insect populations. Brown-headed cowbirds sometimes lay eggs in nests of these sparrows. Their chicks are usually much larger and grow faster than the sparrows, so they get most of the food and the chicks of the parents starve. This is called nest parasitism. (Greenlaw and Rising, 1994)
There are no known negative effects of Nelson's sharp-tailed sparrows on humans.
Nelson's sharp-tailed sparrows do not have any economic benefits for humans.
The number of Nelson's sharp-tailed sparrows is staying constant and they live in a large area. Their biggest threat is loss of habitat from human activities. The grasslands and marshes where they live makes good land for farming, and they need habitat with a specific depth of water. They are protected under the United States Migratory Bird Act, which includes laws about collecting, hunting, and transporting them. ("Ammodramus nelsoni", 2011)
Beth Twaddle (author), Minnesota State University, Mankato, Robert Sorensen (editor), Minnesota State University, Mankato, Rachelle Sterling (editor), Special Projects, Catherine Kent (editor), Special Projects.
MN DNR. 2011. "Ammodramus nelsoni" (On-line). Minnesota Department of Natural Resources. Accessed April 27, 2011 at http://www.dnr.state.mn.us.
BirdLife International. 2009. "IUCN Red List of Threatened Species: Ammodramus nelsoni" (On-line). International Union for Conservation of Nature and Natural Resources. Accessed May 18, 2011 at http://www.iucnredlist.org/apps/redlist/details/150504/0.
Montana Natural Heritage Program and Montana Fish, Wildlife and Parks. 2011. "Nelson's Sparrow — Ammodramus nelsoni" (On-line). Montana Field Guide. Accessed May 01, 2011 at http://fieldguide.mt.gov/detail_ABPBXA0070.aspx.
Cooper, J., S. Beauchesne. 2004. "Nelson's Sharp-tailed sparrow" (On-line). British Columbian Government. Accessed May 01, 2011 at http://www.env.gov.bc.ca/wld/frpa/iwms/documents/Birds/b_nelsonssharptailedsparrow.pdf.
Greenlaw, J., J. Rising. 1994. Saltmarsh Sparrow (Ammodramus caudacutus). The Birds of North America Online, 112: Online. Accessed May 03, 2011 at http://bna.birds.cornell.edu/bna/species/112 doi:10.2173/bna.112.
Shriver, W., T. Hodgman, . Hanson. 2011. Nelson's Sparrow. The Birds of North America (Online), 719: Online. Accessed May 03, 2011 at http://bna.birds.cornell.edu/bna/species/719/articles.
Woolfenden, G. 2007. Wintering Distributions and Migration of Saltmarsh and Nelson's Sharp-Tailed Sparrows. The Wilson Journal of Ornithology, 119: 361- 377. Accessed April 27, 2011 at http://www.jstor.org/stable/20456021.